The objectives of this project are to describe and evaluate the determinants of gastric dysplasia, intestinal metaplasia and chronic atrophic gastritis, conditions thought to be precursors to stomach cancer, in a population in Shandong, China, where stomach cancer rates are high. This will be accomplished by continued follow-up of a population of 3,400 adults age 35-64 classified by: (1) gastric status determined by gastroscopy; (2) diet, tobacco consumption, medical history and other exposures obtained via interviews; and (3) measurements of nutrients and other substances in blood, urine, and gastric juice. Rates of transition of these gastric lesions to cancer will be determined via follow-up of the study population over a 6-year period.